As a nerd, I have a (usually socially unacceptable) impulse to offer 16 possible ways that some plan could go wrong. It's fun, and on occasion useful. It seems very possible to me that your impression of "the state of bioethics" comes from a selection effect, where bioethecists show off their coolest objections to an obviously good thing.

Actually, in engineering school, I learned the same notion -- "shoot lame puppies early". It's a good plan to look for every possible (for a reasonably narrow definition of "possible") way your design could fail before you move further.

All I'm trying to say is that just because these philosophers are talking about cases that probably don't matter doesn't mean that no-one should think about them. On the very small chance that they do matter, the payoffs for having thought about them are large.